Darcs.Patch.Choices

PatchChoices divides a sequence of patches into three sets: first, middle and last, such that all patches can be applied, if you first apply the first ones then the middle ones and then the last ones. Obviously if there are dependencies between the patches that will put a constraint on how you can choose to divide them up. The PatchChoices data type and associated functions are here to deal with many of the common cases that come up when choosing a subset of a group of patches.

forceLast tells PatchChoices that a particular patch is required to be in the last group, which also means that any patches that depend on it must be in the last group.

Internally, a PatchChoices doesn't always reorder the patches until it is asked for the final output (e.g. by get_first_choice). Instead, each patch is placed in a state of definitely first, definitely last and undecided; undecided leans towards middle. The patches that are first are commuted to the head immediately, but patches that are middle and last are mixed together. In case you're wondering about the first-middle-last language, it's because in some cases the yes answers will be last (as is the case for the revert command), and in others first (as in record, pull and push).

Some patch marked middle may in fact be unselectable because of dependencies: when a patch is marked last, its dependencies are not updated until patchSlot is called on them.

Documentation

data PatchChoices p x y

patchChoices :: Patchy p => FL p x y -> PatchChoices p x y

patchChoicesTps :: Patchy p => FL p x y -> (PatchChoices p x y, FL (TaggedPatch p) x y)

Tag a sequence of patches.

patchChoicesTpsSub :: Patchy p => Maybe Tag -> FL p x y -> (PatchChoices p x y, FL (TaggedPatch p) x y)

Tag a sequence of patches as subpatches of an existing tag. This is intended for use when substituting a patch for an equivalent patch or patches.

patchSlot :: forall p a b x y. Patchy p => TaggedPatch p a b -> PatchChoices p x y -> (Slot, PatchChoices p x y)

patchSlot' :: Patchy p => TaggedPatch p a b -> StateT (PatchChoices p x y) Identity Slot

getChoices :: Patchy p => PatchChoices p x y -> (FL (TaggedPatch p) :> (FL (TaggedPatch p) :> FL (TaggedPatch p))) x y

getChoices evaluates a PatchChoices into the first, middle and last sequences by doing the commutes that were needed.

refineChoices :: (Patchy p, Monad m, Functor m) => (forall u v. FL (TaggedPatch p) u v -> PatchChoices p u v -> m (PatchChoices p u v)) -> PatchChoices p x y -> m (PatchChoices p x y)

refineChoices act performs act on the middle part of a sequence of choices, in order to hopefully get more patches into the first and last parts of a PatchChoices.

separateFirstMiddleFromLast :: Patchy p => PatchChoices p x z -> (FL (TaggedPatch p) :> FL (TaggedPatch p)) x z

separateFirstFromMiddleLast :: Patchy p => PatchChoices p x z -> (FL (TaggedPatch p) :> FL (TaggedPatch p)) x z

forceFirst :: Patchy p => Tag -> PatchChoices p a b -> PatchChoices p a b

forceFirsts :: Patchy p => [Tag] -> PatchChoices p a b -> PatchChoices p a b

forceLast :: Patchy p => Tag -> PatchChoices p a b -> PatchChoices p a b

forceLasts :: Patchy p => [Tag] -> PatchChoices p a b -> PatchChoices p a b

forceMatchingFirst :: forall p a b. Patchy p => (forall x y. TaggedPatch p x y -> Bool) -> PatchChoices p a b -> PatchChoices p a b

forceMatchingLast :: Patchy p => (forall x y. TaggedPatch p x y -> Bool) -> PatchChoices p a b -> PatchChoices p a b

selectAllMiddles :: forall p x y. Patchy p => Bool -> PatchChoices p x y -> PatchChoices p x y

makeUncertain :: Patchy p => Tag -> PatchChoices p a b -> PatchChoices p a b

makeEverythingLater :: Patchy p => PatchChoices p x y -> PatchChoices p x y

makeEverythingSooner :: forall p x y. Patchy p => PatchChoices p x y -> PatchChoices p x y

data TaggedPatch p x y

Instances

MyEq p => MyEq (TaggedPatch p)

Commute p => Commute (TaggedPatch p)

Invert p => Invert (TaggedPatch p)

Merge p => Merge (TaggedPatch p)

PatchInspect p => PatchInspect (TaggedPatch p)

data Tag

TG mp i acts as a temporary identifier to help us keep track of patches during the selection process. These are useful for finding patches that may have moved around during patch selection (being pushed forwards or backwards as dependencies arise).

The identifier is implemented as a tuple TG mp i. The i is just some arbitrary label, expected to be unique within the patches being scrutinised. The mp is motivated by patch splitting; it provides a convenient way to generate a new identifier from the patch being split. For example, if we split a patch identified as TG Nothing 5, the resulting sub-patches could be identified as TG (TG Nothing 5) 1, TG (TG Nothing 5) 2, etc.

Instances

Eq Tag

Ord Tag

tag :: TaggedPatch p x y -> Tag

tpPatch :: TaggedPatch p x y -> p x y

data Slot

See module documentation for Choices

Constructors

InFirst

InMiddle

InLast

substitute :: forall p x y. Patchy p => Sealed2 (TaggedPatch p :||: FL (TaggedPatch p)) -> PatchChoices p x y -> PatchChoices p x y

substitute (a :||: bs) pcs replaces a with bs in pcs preserving the choice associated with a